1. Field of the Invention
This invention relates to an improvement in a valve operating system of an internal combustion engine, and more particularly to a valve operating system which is adapted to reduce noise generated thereby.
2. Description of the Prior Art
In connection with a valve operating system using rocker arms of an internal combustion engine, a so-called valve clearance exists between a valve stem and an end section of the rocker arm, and therefore a forceful collision occurs between the valve stem and the the rocker arm, or between the rocker arm and a cam, thereby generating rocker noise which is offensive to the ear. In order to render the valve clearance zero, it has been proposed, for example, to use hydraulic valve lifters. However, this unavoidably complicates the configuration of the valve operating system while increasing the inertial mass of the parts of the valve operating system.